
where \(\hat{m}_{l}\equiv m_{l}/\sqrt{q^{2}}\) , \(p=\sqrt{Q_{+}Q_{-}}/(2M_{1})\) 
with \(Q_{\pm }=(M_{1}\pm M_{2})^{2}-q^{2}\)  and \(M_{1}=m_{\Xi _{c}}\) ,
\(M_{2}=m_{\Xi }\) . The helicity amplitudes \(H_{\lambda _{2},\lambda _{W}}\) ,
which are written in terms of the form factors, can be found in [1]}.
